bug#33232: `gnus-summary-line-format' padding doesn’t work in gui when there are multiple-column-width characters

[Eric Abrahamsen <eric@ericabrahamsen.net>]

On 11/01/18 19:26 PM, Noam Postavsky wrote:
> Eric Abrahamsen <eric@ericabrahamsen.net> writes:
>
>> "Garreau, Alexandre" <galex-713@galex-713.eu> writes:
>>
>>> Given this (rectangular) excerpt from my bug-gnu-emacs summary:
>>>> …01-nov…[-> 33224@debbugs.gnu.org        ] bug#33224: `message-simpli…
>>>> …01-nov…[Noam Postavsky                  ] bug#33225: [debbugs.el] Do…
>>>> …01-nov…[-> Noam Postavsky               ]  bug#33225: [debbugs.el] D…
>>>> …01-nov…[積丹尼 Dan Jacobson             ] bug#33226: chromium, firef…
>>>
>>> On my system (Debian, with Xorg, i3, GUI Emacs), the last line has its
>>> “]” sooner than the others.  This is because `gnus-correct-length'
>>> (along with `char-width') says each of the first three characters is
>>> two-columns wide: but under GUI, this is untrue, as these three
>>> collectively form exactely 5 columns (and not six, as would calculate
>>> `gnus-correct-length').
>>
>> Someone just reported something similar on the org list, that
>> `string-width' doesn't return the actual width occupied by the string,
>> which you'd think would be the whole point.
>
> See Bug#31588, the width of these characters depends on the font, so
> string-width (which works only on a string) can't give the right answer.
> Or, from another point of view, it's the font's fault for being too
> narrow on these characters.

Yeah, I figured it was probably a font issue, but still it's kind of
misleading to have a function that *sounds* like it's going to handle
the font issue, but doesn't.

>> (BTW, it looks like `gnus-correct-length' can be replaced by
>> `string-width'.)
>
> Yep.

Made a bug report.